In general, electron gun x-ray generators have conventionally been known as x-ray sources. In electron gun x-ray generators, most of the energy of electrons that implanted in a target is converted to heat with an efficiency of conversion to x-rays that is extremely low, as low as 0.1%, and so far, it has been an important object to elevate this efficiency of conversion.
X-ray sources employing a hemimorphic crystal have recently attracted attention as a means for achieving this object (see, for example, Non-Patent Document 1). Hemimorphic crystals are also referred to as pyroelectric crystals, and have properties such that when the temperature thereof is elevated and lowered though repeated heating and cooling, spontaneous polarization within the crystal increases or decreases and the charge attracted on the surface fails to follow this change, in such a manner that electrical neutralization is broken. An LiNbO3 single crystal can be cited as a typical hemimorphic crystal, and within this crystal, the center of balance of positive charge (Li+ and Nb5+) and the center of balance of negative charge (O2−) do not coincide, so that the crystal is polarized in a steady state, where a charge having an equivalent amount to this amount of charge and the opposite sign is attracted to the surface of the crystal, and thereby, the crystal is electrically neutralized under normal circumstances.
FIG. 8 shows the configuration of an example of a conventional x-ray generator employing a hemimorphic crystal. Referring to FIG. 8, a heater/cooler plate 52 is arranged as a support on the bottom within a package 51 that is maintained in a low pressure gas atmosphere, and on the upper surface of this, a hemimorphic crystal 53 is arranged so that the surface thereof having positive electricity is supported in such a manner that the surface having negative electricity, which is upwardly exposed, faces a target 54 made of copper that forms the upper surface of the package 51. A beryllium window 55 which is transparent to x-rays and is air tight is mounted on the upper surface of the target 54. A grounding line 56 is connected to the package 51, which is maintained at the grounding potential, and furthermore, a line 57 for applying a direct current voltage to the heater/cooler plate 52, and a temperature controlling signal line 58 are connected to the package 51 so as to generate a heating cycle for elevating and lowering the temperature starting from room temperature (see, for example, Non-Patent Document 2).
In this conventional x-ray generator, it is assumed that charged particles or electrons which are released from the surface having negative electricity due to a change in the electric field, primarily caused by an increase or decrease in the charge on the surface having negative electricity and the surface having positive electricity at the time when the temperature rises and drops, release and excite gas (particularly, O2 molecules) within the package, and as a result, the ionized electrons are made to collide with the target, and thus, x-rays are excited.
In this configuration, however, a problem arises where the intensity of x-rays that are generated in the unit is low and not inappropriate for practical use, and the x-rays are generated only in a discontinuous manner at the time when the temperature of the hemimorphic crystal rises and drops.
In addition, in the prior art, the following ozone generators have been proposed; an ozone generator employing excitement of a gas including oxygen with ultraviolet rays or a laser, an ozone generator employing high voltage discharge, referred to as silent discharge and the like (see Patent Document 1).
These conventional systems for generating ozone, however, require a power supply unit of a high voltage large power of several hundred thousand volts, and therefore, ozone generators to which these systems are applied need a large installment space and consume a large amount of power, making them inconvenient for use in food stores, restaurants, hotels and kitchens.    Patent Document 1: Japanese Unexamined Patent Publication H8 (1996)-33886    Non-Patent Document 1: Science Magazine “Nature” (volume 358, p. 278, 1992)    Non-Patent Document 2: Commodity Catalogue “AMPTEK X-RAY GENERATOR WITH PYROELECTRIC CRYSTAL COOL-X” by AMPTEK INC., delivered from a homepage on the internet, URL: www.amptek.com